Molten metal pump



Aug. 27, 1968 'R. R. RADER MOLTEN METAL PUMP 4 Sheets-Sheet 1 Filed Oct. 25, 1966 smlu 'lllulllllll lillllllllllll INVENTOR. ROBERT R. RADER BY mgy m x A 7' TOENEKS Aug. 27; 1968 R. R. RADER MOLTEN METAL PUMP 4 Sheets-Sheet 5 Filed Oct. 25, 1966 w 7 fi gww mmmmmmmmmma K TIG. 5 INVENTOR.

' ROBERT R. RADER 7, 1968 R. R. RADER 3,398,697

MOLTEN METAL PUMP Filed Oct. 25, 1966 4 Sheets-Sheet 4 INVENTOR. ROBERT R. RADER 47 TORNEYS United States Patent 3,398,697 MOLTEN METAL PUMP Robert R. Rader, Port Huron, Mich., assignor to Wirtz Manufacturing Co., Inc., Port Huron, Mich., a corporation of Michigan Filed 06. 25, 1966, Ser. No. 589,256 18 Claims. (Cl. 103-158) This invention relates to a molten metal pump and more particularly to a piston type displacement pump for moving or displacing molten materials such as lead.

It is an object of the present invention to provide a molten metal pump of the type described which includes a discharge valve mechanically connected to a moving cylinder cup so that the power source used to elfect the suction or intake stroke of the pump can be utilized to pull the discharge valve to the closed position at the end of the intake stroke and thereby produce a tight shutoff of the discharge line for short or long dwell periods.

Another object of the invention is to provide a pump of the type described with an adjustable volume discharge bleed-back after each power stroke of the pump. This feature of the present pump construction is important in installations where the pump is used to supply an overflow type of ladle. The controlled bleed-back permits heating the molten lead in the discharge line between the pump and the ladle to a higher temperature than the lead pot without continual drippage from the ladle resulting from the expansion of the lead due to its increased temperature.

A further object of the present invention is to provide a pump of the type described wherein the working parts are coaxially aligned so that the working forces are coaxial. This allows various parts of the pump to float without the need of auxiliary sliding guides which might otherwise be required to overcome imbalance and which would be subject to wear.

Another object of the present invention resides in the provision of a pump of the type described having a short compact valve body without stagnant areas therein. By carefully sizing and locating the flow passageways through the pump good velocity without excess pressure drop is achieved. In turn this make for trouble-free operation of the pump over long periods of time as compared with other molten metal pumps which are subject to clogging or accumulating dross.

Another object of this invention is to provide in a pump of the type described a valve member formed of a hard material which is capable of retaining good physical properties at the temperatures encountered and which is sufliciently durable to withstand high loading forces so that it is capable of closing down on agglomerated dross and foreign particles that might be present in the molten metal.

A further object of the present invention is to provide a pump of the type described that is admirably suited for operation by means of fluid power and which does not require any spring loaded parts.

In the drawings:

FIGURE 1 is a side elevational view, partly in section, of a lead pot provided with the pump of the present invention.

FIGURE 2 is a fragmentary side elevational view, with parts in section and other parts broken away, of the pump of the present invention.

FIGURE 3 is a fragmentary secitonal view of the pump 3,398,697 Patented Aug. 27, 1968 ice showing the parts in the positions they assume on the power stroke of the pump.

FIGURE 4 is a fragmentary sectional view taken on the line 44 in FIG. 3.

FIGURE 5 is a view similar to FIG. 3 showing the parts of the pump in the positions they assume at the end of the intake stroke.

FIGURE 6 is a sectional view along the line 6--6 in FIG. 5.

FIGURE 7 is a sectional view along the line 7-7 in FIG. 5.

FIGURE 8 is a sectional view along the line 88 in FIG. 5.

FIGURE 9 is a sectional view along the line 9--9 in FIG. 5.

In FIG. 1 there is illustrated a conventional lead pot 10 which is heated by a suitable heating device 12, such as a gas or oil fired burner, to maintain a mass of lead 14 within pot 10 in a molten condition. The pump of the present invention is indicated generally by reference numeral 16. Pump 16 generally includes a pump body 18 and a vertically reciprocable cylinder cup 20 which is driven by an air or other fluid cylinder 22. More specifically, the pump is supported as by a main support arm 24 so that the cylinder cup 20 and the lowerend of the pump body 18 are submerged in the bath 14 of the molten lead. Cylinder 22 is supported over the lead pot 10 in an elevated position by a plurality of vertically extending stand-off rods 26 having their lower ends connected to support arm 24 and their upper ends connected to a cylinder mounting plate 28 on which the cylinder is secured. A discharge line 30 from pump body 18 extends upwardly above lead pot 10 to a ladle 32 which, for example, may be of the overflow type so that during each stroke of the pump a quantity of lead is discharged into ladle 32 which causes the ladle to overflow and discharge into a mold or other device which is being filled with lead. In the arrangement illustrated, a portion of the discharge line 30 extending to ladle 32 is enclosed in a jacket 34 for heating the lead in the discharge line to a temperature higher than the lead in bath 14. An arrangement of this type is common and in many instances found desirable so that the temperature of the lead pot can be maintained at a lower value than required for the actual casting operation.

As is shown in FIG. 2, cylinder 22 has a piston rod 36 extending downwardly through mounting plate 28 and has connected to its lower end as by nuts 38 a cross bar 40'. The opposite ends of cross bar 40 are provided with outwardly opening recesses which receive the upper ends of a pair of pull rods 42. Pull rods 42 are secured to cross bar 40 by nuts 44 and are prevented from shifting outwardly in the recesses at the ends of cross bar 40 by cotter pins 46. The lower ends of pull rods 42 are threaded into sockets 48 in cylinder cup 20 and are locked therein by set screws 50 (FIG. 3). Pump body 18 is secured to support arm 24 by a screw 52.

The stroke of cylinder 22 is adjusted by any suitable means. In the arrangement illustrated an adjusting screw 54 is provided at the upper end of the cylinder for determining the extent of axial movement of the piston in the cylinder. The admission of fluid under pressure to the opposite ends of cylinder 22 is controlled by a solenoid valve 56 which is actuated by a timer or the like to control the speed of reciprocation of piston rod 36 and the frequency of operation.

Referring now to FIG. 3, cylinder cup 20 has an upwardly opening cavity 58 which provides a pump chamher. The inner periphery of the pump side wall that defines chamber 58 is a cylindrical bore as indicated at 60. The bottom wall 62 of the cup 20 is centrally apertured as at 64 to slidably receive a pull rod 66. At its lower end pull rod 66 is fashioned with an inwardly necked portion 68 and a head 69 onwhich a split retainer block 70 is secured by a pair of screws 72. When piston rod 36 shifts downwardly, cup 20 is shifted downwardly by pull rods 42 so that the bottom wall 62 of cup 20 engages retainer block 70 and urges pull rod 66 in a downwardly direction.

Pump body 18 has a downwardly opening bore 74 at its lower end. The upper end of bore 74 is formed with radial outlet port 76 to which the lower' end of discharge line 30 is connected. Within bore 74 there is arranged a valve retainer 78 which is clamped upwardly against a shoulder 80 by a second valve retainer 82 which is threaded into the lower end of bore 74 as at 84. Retainer 82 is of a hollow cylindrical shape and at its lower end it is fashioned with a radially outwardly extending flange 86 and a radially inwardly extending flange 88. Between the flange 86 and the lower end face 90 of valve body 18 there is arranged a plunger ring 92. The annular end face 90 of body 18 is accurately ground so that the top face 94 of ring 92 is adapted to seat thereagainst and form a seal therebetween. As is shown in FIG. 4, the lower end of retainer 82 is fashioned with a plurality of flats 96 so as to provide annular segment-shaped intake passageways 98 for the flow of metal from the lead pot into the chamber 58 of cylinder cup 22 (FIG. 5).

Plunger ring 92 has a sliding fit with the inner cylindrical surface 60 of the cup 20. Plunger ring 92 is preferably made of steel; consequently it has a lower specific gravity than molten lead and tends to float upwardly into engagement with the sealing end surface 90 at the lower end of pump body 18.

Within retainer 82 there is arranged a valve seating ring 100 that is frictionally retained with-in the bore 102 of the retainer 82 against the shoulder formed by the radially inwardly extending flange 88. The central aperture 104 accommodates the pull rod 66 which extends upwardly therethrough and has a valve member 106 secured thereto by a screw 108. A large recess 110 in the upper face of the valve member 106 accommodates the head 112 of screw 108 so that the screw forms a swivel connection between pull rod 66 and valve member 106. The lower face of valve member 106 is fashioned with an annular groove 114 that forms a narrowland 116 around the outer periphery of valve member 106. Land 116 is adapted to be brought into tight sealing engagement with the upper face of seating ring 100 as shown in FIG. 5. The upper open end of valve member 106 is closed by a cover 118 which is crimped on valve member 106 as at 120 and which is provided with four radially outwardly extending lugs 122 that engage the bore 102 of retainer 82 and, thus, vertically guide valve member 106 in retainer 82.

Retainer 78 has a central bore 124 which is enlarged at the lower end of the retainer as at 126. A plurality of headed rivets or studs 128 extend through retainer 78 and are welded or otherwise secured in place with their lower ends projecting into the enlarged bore 126. The heads 130 at the upper ends of studs 128 are spaced above the top face of retainer 78 and serve to limit the upward movement of a damper valve disc 132 arranged on the upper face of retainer 78. The lower ends of studs 128 lie in a common plane and serve as a stop surface for the upward movement of valve member 106. Damper valve disc 132 is preferably formed of a material such as tungsten-carbide which has a specific gravity greater than molten lead. Thus, damper valve disc 132 normally tends to remain seated on the upper end of retainer 78 to seal bore 124. However, the upper face of retainer 78 has a radial groove 134 machined therein such that, even when valve disc 132 is seated on retainer 78, a certain amount of molten lead is permitted to bleed-back downwardly through the pump through the passageway formed by groove 134.

In FIG. 3 the parts are illustrated at the end of the power stroke of cylinder cup 20. During the power stroke cylinder cup 20 is pulled upwardly by pull rods 42. The buoyant force on plunger ring 92 and the friction between plunger ring 92 and the bore 60 of chamber 58 cause ring 92 to shift upwardly into sealing engagement with the lower end face of valve body 18. During the power stroke of the pump, cylinder cup '20 shifts vertically from the position shown in FIG. 5 'to that shown in FIG. Thus, the pump chamber 58 is progressively reduced in volume and the lead trapped therein is cause to flow upwardly through the pump body, following the path 1ndicated by the arrows in FIG. 3. The discharge passageway from pump chamber 58 comprises central aperture 104 of the valve seating ring 100, then around valve member 106 and cover 118 to the bore 126 of retainer 78. The lead then flows upwardly through bore 124 and flows upwardly to the discharge line 30 through the outlet port 76. The lead flowing upwardly through discharge line 30 is directed to overflow ladle 32. At the end of the power stroke of the pump, valve disc 132 seats on the upper surface of retainer 78 and prevents a free flow of lead from ladle 32 back into lead pot 10. However, a controlled amount of bleed back of lead from ladle 32 to pump chamber 58 is permitted by groove 134 until such time as valve member 106 is caused to seat on ring 100.

On the intake or suction stroke of the pump, cup 20 is forced downwardly from the position shown in FIG. 3 to the position shown in FIG. 5 by pull rods 42. As soon as cup 20 starts moving downwardly from the position shown in FIG. 3, the reduced pressure in the enlarging pump chamber 58 and the friction between plunger ring 92 and the bore 60 of cup 20 causes ring 92 to shift downwardly from sealing relationship with the end face 90 of pump body 18 and open the intake passage from the lead pot 10 to the pump chamber 58, the lead flowing through the arcuate passageways 98 .as shown by the arrows in FIG. 5. Eventually the bottom wall 62 of cup 20 engages the retainer block 70 at the lower end of pull rod 66 and shifts the pull rod downwardly. When this occurs, the head 112 of screw 108 engages valve member 106 and shifts it downwardly. Eventually the narrow land 116 around the lower end of valve member 106 is brought into sealed engagement with the upper face of ring 100. Valve member 106 effectively seals the discharge passageway since the downward force exerted by cylinder 22 is applied as a relatively high unit pressure around the narrow land 116. This high unit pressure coupled with the swiveled connection between valve member 106 and pull rod 64 effectively closes the discharge passageway at the seating ring 100.

It is apparent from the forgoing description that valve member 106 can be pulled closed against seating ring by hundreds of pounds of force to assure a tight shutoff of lead flow and the maintenance of a given volume of molten material at a predetermined head height above and beyond valve member 106. However, as soon as the cylinder cup 20 starts its power or displacement stroke, the seating load on valve 106 drops immediately to zero so that the pump does not have to overcome a seating load on the discharge valve 106 as is the case with spring loaded valves.

The amount of bleed-back which occurs through the groove passageway 134 during the suction stroke of cup 20 can be easily regulated by controlling either the dwell at the end of the pump displacement stroke or the speed of the air cylinder during the suction stroke or both. This bleed-back occurs in the time period between the end of the displacement or power stroke and the end of the suction stroke. Any means for controlling this time interval will necessarily control the amount of bleed-back from ladle 32 into the pump chamber 58. This controlled bleed-back is an important feature of the present invention when the pump is used in combination with an overflow ladle. In such arrangements the molten lead in the discharge line 30 is normally heated to a temperature above the temperature of the lead in bath 14. Upon heating, the lead expands and, in the absence of a bleedback of lead to the pump chamber there would be a continual dripping of the lead from the overflow port of the ladle. Thus, by controlling the amount of bleedback, the discharge from the overflow ladle can be controlled to an accurate amount during each displacement stroke of the pump.

The use of a power cylinder such as shown at 22 is desirable from the standpoint of simplicity, ease of control and ease of removal of the pump assembly from the molten bath. It is apparent, however, that the invention is not limited to operation of the pump by air or other fluid cylinders. Many common arrangements are practical for vertically reciprocating cup including levers, cams, screws, etc.

Iclaim:

1. A pump adapted to be immersed in a bath of molten material for pumping the material from the bath to a remote delivery point comprising a pump body, means for supporting the pump body in fixed position with an end portion thereof submerged in a bath of molten material, a cup member telescopically arranged with said end portion of the pump body and adapted to form a pump chamber therewith, means for reciprocating said cup member axially to increase the effective size of said pump chamber when the cup member is shifted axially in one direction and to decrease the effective size of the pump chamber when the cup member is shifted axially in the opposite direction, an inlet passageway extending to said pump chamber from exteriorly of the cup member, valve means controlling said inlet passageway and responsive to travel of the cup in said one direction to admit material from the bath in which the pump is immersed to said pump chamber and to prevent discharge of material from said pump chamber through said inlet passageway when the cup member is moved in the opposite direction, a discharge passageway in said pump body communicating at one end with said pump chamber, a discharge valve controlling said discharge passageway and means mechanically interconnecting said discharge valve with said cup memher so that the discharge valve is actuated by said cup member to a position closing said discharge passageway when the cup member is shifted axially to the end of its stroke in said one direction, said interconnecting means permitting the discharge valve to shift to a position open ing said discharge passageway when the cup member is shifted in said opposite position.

2. A pump as called for in claim 1 wherein the side wall of the cup member at the open end thereof is spaced radially from the telescoped end portion of the pump body and in part defines said inlet passageway, said inlet valve comprising a ring movable axially in said space, said space being defined adjacent one axial end thereof by a valve seat against which said inlet valve is adapted to abut to close said inlet pasageway when the cup member is shifted axially in said opposite direction.

3. A pump as called for in claim 1 including a second valve in said discharge passageway located downstream from said cup member actuated valve, said second valve in the discharge passageway being adapted to close the discharge passageway when the cup member is initially shifted in said one direction and to open the discharge passageway when the cup member is shifted axially in said opposite direction.

4. A pump as called for in claim 3 including means associated with said last-mentioned valve and forming a bleed orifice for permitting a controlled bleed-back of pumped material to said pump chamber when the cup member is shifted in said one direction and prior to the closing of the first-mentioned valve in the discharge passageway.

5. A pump as called for in claim 1 wherein the pump body is supported such that the lower end thereof is adapted to be immersed in said bath of molten material, said cup member being telescoped over the lower end of said body and being disposed with its reciprocating axis extending generally vertically.

6. A pump as called for in claim 4 wherein said one direction is downwardly and said opposite direction is upwardly.

7. A pump as called for in claim 6 wherein the Wall of the cup member adjacent its open upper end is spaced radially outwardly from the outer periphery of the lower end portion of the pump body and cooperates therewith to define said inlet passageway, said valve in the inlet pasageway comprising a ring movable vertically in the annular space between the wall of the cup member and the outer periphery of the lower end portion of the pump body.

8. A pump as called for in claim 7 wherein said lower end portion of the pump body has a downwardly facing shoulder thereon against which said ring is adapted to seat to close the inlet passageway.

9. A pump as called for in claim 8 wherein said ring is formed of a material having a lower specific gravity than the bath of molten material in which the pump is adapted to be immersed so that the bouyant force of :said molten material will tend to seat said ring on said shoulder.

10. A pump as called for in claim 9 wherein the outer periphery of said ring slidably contacts the inner surface of the wall of the cup member.

11. A pump as called for in claim 1 wherein said discharge passageway is formed with a horizontally disposed seat portion, said cup member being adapted to pull the first-mentioned discharge valve downward into sealing engagement with said seat portion.

12. A pump as called for in claim 1 wherein the axis of reciprocation of the cup member is vertical, said discharge passageway being formed with a horizontally disposed valve seat portion, said cup member being adapted to pull the discharge valve downwardly into sealing engagement with said seat portion when the cup member approaches the lower end of its stroke.

13. A pump as called for in claim 11 wherein said discharge valve has a center opening extending vertically therethrough, said interconnecting means comprising a vertically extending rod connected at its lower end with said cup member such that the cup member is adapted to pull the rod downwardly on its down stroke, said rod extending upwardly through said central opening and having an enlarged head overlying the discharge valve and adapted to seal said central opening when the cup member is shifted downwardly to the lower end of its stroke.

14. A pump as called for in claim 13 wherein said rod has a swivel connection with said discharge valve.

15. A pump as called for in claim 13 wherein said discharge valve member is adapted to be pulled downwardly by said enlarged head into sealing engagement 'with said horizontally disposed seat portion to limit the downward stroke of said cup member.

16. A pump as called for in claim 6 including a damper valve in said discharge passageway located downstream of said discharge valve, said damper valve being adapted to open said discharge passageway when the cup member is shifted upwardly and to close the discharge passageway when the cup member is shifted downwardly and means associated with said damper valve forming a bleed passagew-ay permitting a controlled bleed-back of pumped material to said pump chamber after said damper valve closes and prior to the closing of said discharge valve.

17. A pump as called for in claim 16 wherein the damper valve is adapted to open in an upward direction References Cited and close in response to gravity, said damper valve being UNITED STATES PATENTS formed of material having a specific gravity greater than that of the molten material in which the pump is adapted to 1646'134 10/1927 l 103 225 1,857,026 5/1932 Llgon 103-158 be immersed. 5 5 /1 5 18. A pump as called for in claim 1 wherein the means 2 3 1 1 2 Hal'ward 1O3 '1 8 for reciprocating said cup member comprises a fluid cylin- 8 3 :32:; der having a piston rod connected with said cup member, 3:263:622 8/1966 y e "it: 1O3 158 said cylinder being spaced axially of said cup member and connected thereto by axially extending pull rods. 10 HENRY F. RADUAZO, Primary Examiner. 

1. A PUMP ADAPTED TO BE IMMERSED IN A BATH OF MOLTEN MATERIAL FOR PUMPING THE MATERIAL FROM THE BATH TO A REMOTE DELIVERY POINT COMPRISING A PUMP BODY, MEANS FOR SUPPORTING THE PUMP BODY IN FIXED POSITION WITH AN END PORTION THEREOF SUBMERGED IN A BATH OF MOLTEN MATERIAL, A CUP MEMBER TELESCOPICALLY ARRANGED WITH SAID END PORTION FOF THE PUMP BODY AND ADAPTED TO FORM A PUMP CHAMBER THEREWITH, MEANS FOR RECIPROCATING SAID CUP MEMBER AXIALLY TO INCREASE THE EFFECTIVE SIZE OF SAID PUMP CHAMBER WHEN THE CUP MEMBER IS SHIFTED AXIALLY IN ONE DIRECTION AND TO DECREASE THE EFFECTIVE SIZE OF THE PUMP CHAMBER WHEN THE CUP MEMBER IS SHIFTED AXIALLY IN THE OPPOSITE DIRECTION, AN INLET PASSAGEWAY EXTENDING TO SAID PUMP CHAMBER FROM EXTERIORLY OF THE CUP MEMBER, VALVE MEANS CONTROLLING SAID INLET PASSAGEWAY AND RESPONSIVE TO TRAVEL OF THE CUP IN SAID ONE DIRECTION TO ADMIT MATERIAL FROM THE BATH IN WHICH THE PUMP IS IMMERSED TO SAID PUMP CHAMBER AND TO PREVENT DISCHARGE OF MATERIAL FROM SAID PUMP CHAMBER THROUGH SAID INLET PASSAGEWAY WHEN THE CUP MEMBER IS MOVED IN THE OPPOSITE DIRECTION, A DISCHARGE PASSAGEWAY IN SAID PUMP BODY COMMUNICATING AT ONE END WITH SAID PUMP CHAMBER, A DISCHARGE VALVE CONTROLLING SAID DISCHARGE PASSAGEWAY AND MEANS MECHANICALLY INTERCONNECTING SAID DISCHARGE VALVE WITH SAID CUP MEMBER SO THAT THE DISCHARGE VALVE IS ACTUATED BY SAID CUP MEMBER TO A POSITION CLOSING SAID DISCHARGE PASSAGEWAY WHEN THE CUP MEMBER IS SHIFED AXIALLY TO THE END OF ITS STROKE IN SAID ONE DIRECTION, SAID INTERCONNECTING MEANS PERMITTING THE DISCHARGE VALVE TO SHIFT TO A POSITON OPENING SAID DISCHARGE PASSAGEWAY WHEN THE CUP MEMBER IS SHIFTED IN SAID OPPOSITE POSITION. 